Introduction

Web service is a standardized means of spreading communication between client and server applications (World Wide Web). A web service is a software module develop to perform specific tasks.

Web services in cloud computing can be search for in the network and called up accordingly.

When the web service is call, it can provide the functionality for the client calling that web service.

How Do Web Services Work?

This requirements are made through so-call remote procedure calls. Remote Procedure Calls (RPCs) are calls to methods hosted by the corresponding web service.

For example, Amazon proposals a web service that offers prices for products sold online on amazon.com. The front or presentation layer can be .Net or Java, but both programming languages ​​can communicate with the web service.

The main component in the design of a web service is the data that is transfer between the client and server, i.e., XML. XML (Extensible Markup Language) complements HTML and is the easy-to-understand intermediate language many programming languages ​​understand.

Web services use  as a Simple Object Access Protocol (SOAP) to send XML data between applications. The data is sent over regular HTTP. The data sent to the application by the web service is known as a SOAP message. The SOAP message is nothing more than an XML document. Because the document is written in XML, the client application calling the web service can be write in any programming language.

Why Do You Need A Web Service?

Business applications today use a variety of programming platforms to develop web applications. Some applications can be create in Java, others in .Net, while others in Angular JS, Node.js, etc.

Most of the time, these heterogeneous applications need some communication between them. Since they are created with different development languages, it isn’t easy to ensure precise communication between the applications.

This is where web services arise into play. Web services provide a common platform that enables multiple applications written in different programming languages ​​to communicate.

Type Web Service

SOAP Web Services

It is base on the transmission of XML data in SOAP messages. Each message contains a so-called XML document. Only the XML document structure follows a specific pattern, but not the content. The best thing about SOAP and web service is that everything is sent to HTTP, the standar web protocol.

Every SOAP document must have the <Envelope> element’s root element. The root component is the first element in an XML document.

The “envelope” is divide into two parts. The first is the header, and the next is the body.

The body contains the actual message.

Example Web Service

In the web service examples, we have two messages exchanged between the web service and the client application. One is the “Tutorial Request” operation, and the other is the “Tutorial Response” operation. Tutorial Request contains an element called “tutorial,” a type string. The Tutorial Response operation also includes a feature called “Tutorial Name,” a string type. <message> – The Message parameter in the WSDL definition is used to define the various data elements for each operation performed through the web service.

<port Type>: It describes the web service’s operation, which is call a tutorial. This process can require two messages; one is an input message, and the other is the output message.

<binding>: This element contains the protocol used. In our case, we set it to use HTTP (http://schemas.xmlsoap.org/soap/http). We also give other details for the central part of the operation, such as B. the namespace and whether the message should be prearrange.

Benefits Of Web Services

We already understand why web services were born in the first place, namely to provide a stage for different applications to communicate.

But let’s take a look at the list of benefits of web services as to why it is essential to use them.

Exposing Business Functions Over The Network: A web service is a managed code unit that provides specific functionality to client applications or end-users. This feature is accessible via the HTTP protocol, which is also accessible via the Internet. Nowadays, all applications are on the Internet, making web services more valuable. This means that the web service can be located anywhere on the Internet and provide the required functionality as needed.

Interoperability Between Applications: Web services allow multiple applications to communicate and share data and services. All types of requests can communicate with each other. So instead of writing specific code that only certain applications can understand, you can now write generic code that all applications can understand.

Web Services Architecture

Every framework needs some sort of architecture to make sure that the whole framework works as expected, similar to what happens with web services. The architecture of web services consists of three different roles:

Provider – The provider creates the web service and makes it available to the client application that wants to use it.

Requestor – A requestor is nothing more than the client application to contact a web service. The client application can be .Net, Java, or any other language-based application that looks for some functionality through a web service.

Broker: The broker is nothing more than the application that provides access to the UDDI. As described in the previous topic, UDDI allows the client application to find the web service.

Web Services Characteristics

Web services have the following specific behavioral characteristics:

They are XML-base: Web services use XML to represent transport and data representation layers. Using XML eliminates any network, operating system, or platform dependency because XML is the common language that everyone understands.

Loosely coupled: Loosely coupled means the client and web service are not connect, i.e., That is, even if the web service changes over time, the way the client calls the web service should not change. The assumption of a weakly coupled architecture makes software systems easier to handle and allows more accessible integration between different systems.